Specifications

ATAPI For Streaming Tape QIC-157 Rev B
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data most recently encountered during a prior read operation. This is the case in the boundaries shown
in Table 6-51.
Table 6-51 Boundaries that generate a “Check Condition” when RED field is one
Prior Data Current Data Sense Key
uncompressed compressed MEDIUM ERROR
(unsupported algorithm)
compressed compressed MEDIUM ERROR
(supported algorithm) (unsupported algorithm)
compressed uncompressed NO SENSE
(unsupported algorithm)
compressed compressed RECOVERED ERROR
(unsupported algorithm) (supported algorithm)
compressed compressed MEDIUM ERROR
(unsupported algorithm A) (unsupported algorithm B)
At each of these boundaries, the data sent to the Host is of a fundamentally different nature from that
which was previously sent.
A RED field of two indicates that the Device shall return a “Check Condition” status when data is
encountered on the medium during a read operation that has been processed using a different algorithm
from that data most recently encountered during a prior read operation. This is the case at the
boundaries shown in Table 6-52.
Table 6-52 Boundaries that generate a “Check Condition” when RED field is zero
Prior Data Current Data Sense Key
uncompressed compressed MEDIUM ERROR
(unsupported algorithm)
uncompressed compressed RECOVERED ERROR
(supported algorithm)
compressed uncompressed NO SENSE
(supported algorithm)
compressed compressed MEDIUM ERROR
(supported algorithm) (unsupported algorithm)
compressed compressed RECOVERED ERROR
(supported algorithm A) (supported algorithm B)
compressed uncompressed NO SENSE
(unsupported algorithm)
compressed compressed RECOVERED ERROR
(unsupported algorithm) (supported algorithm)
compressed compressed MEDIUM ERROR
(unsupported algorithm A) (unsupported algorithm B)
On any of the boundary conditions that results in a “Check Condition” status, the Additional Sense
Code shall be set to either DECOMPRESSION EXCEPTION SHORT ALGORITHM ID OF NN (id
the algorithm identifier & 255) or DECOMPRESSION EXCEPTION LONG ALGORITHM ID. The
Device shall, in both cases, set the decompression algorithm field to the algorithm identifier of the
compression algorithm used to process the encountered data. The Device shall be positioned on the
EOP side of the encountered data, and the Command-Specific Information field in the sense data shall
contain the count of the number of data blocks contained within the encountered data.